Nose fuze for a bomb



April 24, 1956 c. F. BOWERSETT NOSE FUZE FOR A BOMB 4 Sheets-Sheet lFiled Dec. 20, 1946 C. F. BOWERSETT www April 24, 1956 c. F. BowERsETTNOSE FUZE FOR A BOMB 4 Sheets-Sheet 2 Filed Dec. 20, 1946 April 24, 1956c. F. BowERsETT NOSE FUZE FOR A BOMB 4 Sheets-Sheet 5 Filed Dec. 20,1946 Syvum/vrom C. F. BOWERSETT April 24, 1956 c. F. Bowx-:RsETT2,742,859

NOSE FUZE FOR A BOMB C. F. BOWERSETT United States Patent O NOSE FUZEFOR A BMB Charles F. Bowersett, Arlington, Va.

Application December 20, 1946, Serial No. 717,364

4 Claims. (Cl. 10281.2)

(Granted under Title 35, U. S. Code (1952), sec. 266) This inventionrelates to a fuze and more particularly to a mechanically operatedimpact fuze for use on the nose of a bomb, rocket or the like.

The present invention relates to a new and improved impact nose fuze fora bomb or the like adapted to fire instantaneously upon impact of thebomb with the surface of a body of water, sand or terra firma, as thecase may be, and in which means may be also provided such that, ifdesired, explosion of the main charge within the bomb may occur inpredetermined time delayed relation with respect to impact of the bombwith the aforesaid elements. Furthermore, according to one form of theinvention, the present invention provides an impact nose fuze for a bombin which new and improved means are provided such that the fuze will notfunction upon impact of the bomb with the surface of a body of water butwill pass therethrough a predetermined depthsuch, for example, as twentyfeet and tire upon impact of the bomb with the bed of the body of waterthereby to fire the main explosive charge arranged within the bomb.

The present invention provides a fuze for a bomb having new and improvedsafety features incorporated therein such that premature firing of thebomb is prevented should the bomb be accidentally dropped from adistance of 20 feet during handling and transportation. In fuzes of thisgeneral type heretofore devised, should a bomb having a fuze of theprior art type be accidentally dropped by the crew members a distance ofapproximately 20 feet as the bomb is being releasably attached to anaircraft by the crew member, or during transportation thereof prior toattaching the bomb to an aircraft, premature explosion of the bomb wouldoccur provided that the nose thereof struck a hard surface or objectwith suicient force to crush the nose of the bomb inasmuch as thedetonator and tiring pin are aligned at all times, such crushing actionof the nose of the bomb driving the tiring pin into firing engagementwith the detonator and exploding the bomb.

The principal object of the present invention, therefore, is to providean impact nose fuze for a bomb having new and improved means forpreventing premature tiring thereof due to a sudden shock.

Another object is to provide an impact nose fuse in which the detonatoris maintained in a safe locked position and out of alignment with thetiring pin until the bomb is released from an aircraft in flight andarming thereof will occur only when the bomb has traveled apredetermined distance from the aircraft during the free t ight of thebomb toward a target.

Another object of the present invention is to provide a new and improvedmechanically operated nose fuze for a bomb in which premature firingthereof is prevented should the bomb be accidentally dropped a distanceof approximately 20 feet.

Another object is to provide a normally unarmed impact nose fuze for abomb having new and improved armingmeans arranged therein adapted to bemaintained in an initial safe position until the bomb is dropped from2,742,859 Patented pr. 24, 1956 ice an aircraft in flight and in whicharming thereof does not occur except during the free flight of the bombtoward the target.

A further object is to provide an impact nose fuze for' of will occur inpredetermined time delayed relation with respect to impact of the bombwith a target or with the bed of a body of water.

A still further object is to provide a new and improved impact nose fuzefor a bomb which is economical to manufacture, reliable in operation andwhich possesses all the qualities of ruggedness and dependability inservice.

Still other objects, advantages and improvements will be apparent fromthe following description, taken in connection with the accompanyingdrawings, of which:

Fig. l is a central longitudinal sectional View of the fuze and aportion of the bomb to which the fuze is secured, the fuze being shownin an unarmed condition;

Fig. 2 is a view similar to Fig. l but showing the fuze,

in an armed condition;

Fig, 3 is an enlarged sectional view taken on line 3--3 of Fig. l;

Fig. 4 is a view taken on line 4-4 of Fig. 2 and show- Y ing the fuze inan armed condition;

Fig. 5 is a detail view of the fuze showing an alternative form ofstriker head secured thereto; and

Fig. 6 is a view partly in section and partly in elevation and showingthe fuze connected to a rocket.

Referring now to the drawings for a more complete understanding of theinvention wherein like reference characters indicate like partsthroughout the several views, a fragmentary portion of a bomb isindicated generally by the numeral 10 and comprising a casing 11 havingarranged therein the usual explosive charge 12 as is well known to thoseskilled in the art to which the invention pertains.

The bomb may be releasably supported to an aircraft in flight in theusual manner, and an arming wire 13 connected to the aircraft ispreferably employed to prevent rotative movement of the propeller 14secured to the fuze of the present invention and generally indicated bythe reference character 15.

The fuze is supported on the nose of the bomb in any suitable manner butpreferably by a cup-shaped member 16 having threaded engagement with acentrally disposed bore 17 provided in the nose of the bomb, Figs. l and2.

The cup-shaped member 16 has integrally formed thereon The cup-shapedmember 16 is provided with a well23 a portion of which is threaded as at24, and having threaded engagement with a booster cup or container 25.One end of the container 25 is closed by an end wall 26 integrallyformed therewith, the other end thereof being closed by a relativelythick metallic discy 27 disposed between a shoulder 28 formed on thecup-shaped member 16 and the outer end of the booster cup 25, Figs. land 2. Arranged within the booster cup and disposed between the wall 26and the disc 27 is a booster charge 29.A As shown on Figs. l and 2 thebooster cup extends a predetermined distance into the explosive charge12, thereby wall 18 and the disc 27, the purpose of which will be moreclearly apparent as the description proceeds.

Rotatably supported within a bore 32 axially arranged within the head 21is an arming hub generally indicated by the reference character 33. Thearming hub comprises a tubular body 34 having a reduced portion 35formed thereon for supporting a stationary gear 36, the

holder thus is maintained in a safe position by the striker until thestriker is withdrawn from bore 64 after the bomb has been released fromthe aircraft and has traveled a predetermined distance therefrom.

Rotatably supported on a stud 66 and in continuous mesh with the gears36 and 55 is an idle or driving gear gear being secured to the portionof the hub 33 in VVthe thrust bearing 38 is adapted to relieve the axialthrust from the propeller 14 during the free Hight of the bomb toward-the target. Y

As shown on Figs. l and 2 the arming hub 33 has integrally formedthereon a flange 42 having abutting engagement with a shoulder 43 formedin the head 21, the flange being maintained in abutting engagement withthe shoulder 43 by the aforesaid thrust bearing, thereby to preventendwise movement of the arming hub within the head 21. It will beunderstood, however, that the arming hub 33 is free to rotate within thebore 32 provided in the head 21 during the free flight of the bombtoward the target.

The propeller 14 comprises a hub 44 secured to the thrust bearing 38 inany convenient manner but preferably as shown on Figs. 1 and 2. Thesecuring means for the propeller includes a well 45 arranged in thethrust bearing 38 and a lug 46 formed on the hub 44 of the propeller,the lug being adapted to extend a predetermined distance into the wellthereby to lock the propeller 14 to the thrust bearing 38 in such amanner as to impart rotative movement to the thrust bearing during thefree fiight of the bomb toward the target.

The propeller 14 is maintained in locking engagement with the thrustbearing by a retainer nut 47 threaded onto the .arming hub 33 and intoabutting engagement with the thrust bearing Figs. l and 2. From theforegoing description it will be apparent that the arming hub 33, thrustbearing 38, retainer nut 47, and gear 36 will rotate as a unit inresponse to the pressure of air against the propeller blades during thefree flight of the bomb toward the target.

Rotatably and slideably supported within an axial bore 48 arranged inthe arming hub 33 is an arming sleeve 51. The arming sleeve comprises abody 52 having an enlarged threaded portion 53 formed thereon adapted tohave threaded engagement with the bore 48 as at 54. Arranged on one endof the arming sleeve is a gear 55, the gear being staked to the armingsleeve in a well known manner and rotatable therewith, the gear 55having abutting engagement with a ange 56 formed on the arming sleevethereby to maintain the gear xed to the end of the arming sleeve.

A firing pin generally indicated by the reference character 57 isreleasably secured to the arming sleeve 51 by a shear pin 58 Figs. l and2, the shear pin extending through complementary bores provided in thearming sleeve 51 andthe tiring pin 57. Rotative movement of the sleeve52 is imparted to the tiring pin 57 by a non-shearable pin 60 securedthereto and detachably disposed within a recess provided in the innersurface of the sleeve, and thus the shear pin 58 is relieved of anytorsional stress thereon as the sleeve 52 is rotated and also providingaxial movement of the tiring pin inwardly withv respect to the sleeve inresponse to a sudden impact received thereby. Secured to one end of thetiring pin 57 as at 61 is an impact disc 62, the other end thereof beingreduced in 'size to form striker 63 adapted to extend through a bore 67,the movable gear 55 having one tooth more than the stationary gear 36.By this arrangement there is relative rotative motion between the gears36 and 55, such rotation being transferred to the arming sleeve 51through the gear 55. When this occurs, the arming sleeve 51 is movedoutwardly due to the threaded engagement of the arming sleeve with thebore 48. From the foregoing description, it will be apparent that`astructure has been disclosed in which the arming sleeve 51 is adapted torotate at a greatly reduced rate of speed with respect to the rotationof the arming hub and component parts thereof by reason of the planetarygear arrangement disclosed.

The detonator holder or shutter 65 is pivotally mounted within thechamber 31 by a pin 69. The holder comprises a body 71 having integrallyformed thereon a pair of spaced ears 72, each ear being provided with anaperture 73 through which the pivot pin 69 extends. The pin is securedto the end wall 18 of the cup-shaped member 16 in any suitable mannersuch, 'for example, as a press fit. As shown on Figs. 3 and 4, a torsionspring 74 surrounds the pivot pin 69, the convolutions thereof beingdisposed between the ears 72, one leg of the spring being in engagementwith the inner wall surface of the cupshaped member 16, and the otherleg being in engagemen-t with a wall 75 formed on the shutter 65 suchthat when the tiring pin is withdrawn from engagement with the shutterduring the free flight of the bomb toward the target the shutter ismoved to an armed position, Figs. 3 and 4, by the spring 74.

A detonato-r 76 is arranged within an aperture 77 provided in theshutter 65 and adapted to be moved into alignment with a lead-incharge78 arranged in the disc 27 when the shutter has been moved tn an armedposition in engagement with a stop pin 70. It will be obvious that whenthis occurs the detonator is also brought in alignment with the nowretracted ring pin Fig. 4 and the fuze is armed.

As shown on Fig. l the striker 63 is maintained in spaced relation withrespect to the lead-in charge 78 invariably by the impact disc 62secured on one end of the ring pin and having abutting engagement withthe end portion of the arming hub 33. It will be understood, however,should the bomb be accidentally dropped during handling and the impactdisc 62 strikes a hard surface, premature firing of the bomb isprevented as the detonator is in the safe position and out of alignmentwith the firing pin when this occurs. The striker 63 is additionallypreventedfrom being driven into engagement with the lead-in charge 78when the bomb is accidentally dropped and the nose thereof strikes ahard surface by a shoulder 80 formed on the tiring pin and adapted toengage the end Wall 18 of the cup-shaped member 16 thus preventingpremature damage to the lead-iu charge by the striker 63.

The shutter 65 is also provided with a locking detent 79 arranged in abore 81 formed therein and adapted to engage a well 82 disposed in theend wall 18 of the cup-shaped member 16 when the shutter has been movedto an armed position. The detent 79 is urged into the well 82 by aspring 83 arranged in the lbore 81 and having one end thereof inengagement with one end of the detent, the other end of the spring beingseated against the bottom wall of the well 82 thereby to .lock theshutter in an armed position Figs. 2 and 4 when the shutter has beenrotated a predetermined amount by the torsion spring 74, which occursafter the firing pin hasy been withdrawn from engagement with theshutter and during the free flight of the bomb toward the target.

It will be understood, however, that the shutter 65 ,'isnaaintained linan `initialsafeposition by the ringpin 57 'and rotation thereof Vto anarmed position is prevented by the firing pin until the bomb is releasedfrom an aircraft in flight and the propeller 14 has made a predeterminednumber of revolutions such, for example, as 400 revolutions.

As shown on Fig. 1 the propeller 14 is restrained from rotation duringtransportation of the bomb on the aircraft by the aforesaid arming wire13 which is normally arranged in an aperture 84 provided in a guide 85secured to the head 21 of the fuze in any suitable manner but preferablyby'one or more screws 86, the arming wire also extending through one ofa pair of complementary apertures 87 respectively `arranged in a pair ofdiametrically disposed arms 88 formed on the propeller hub 44.

As shown on Figs. 2 and 4 of the drawings, the fuse is in an armedposition, the arming sleeve 51 and ring pin 57 having been movedoutwardly a predetermined amount through the medium of the propeller andplanetary gear arrangement heretofore described, thus releasing theshutter 65 which is rotated to an armed position by the torsion spring74. When this occurs, the tiring pin 57, detonator 76 and lead-in charge78 are in alignment and, upon impact of the bomb with the target, theimpact disc 62 is driven inwardly in response to the force of impactreceived thereby and concurrently therewith the shear pin 58 is severed,whereupon the striker -63 on the tiring pin 57 is driven into thedetonator with suflicient force to re the detonator, the detonator beingadapted to ignite the lead-in charge 78 thereby to ignite the boostercharge 29 which lires the main charge 12 and explodes the bomb. It willbe understood, however, that during the arming of the fuze the propeller14 makes a predetermined number of revolutions during the free ight ofthe bomb toward the target during which time the arming sleeve 51 isalso adapted to rotate a predetermined lesser number of revolutions andthe arming sleeve will move outwardly due to the threaded engagementthereof with the threaded portion 54 of the bore 48 until the gear 55 onthe arming sleeve engages the gear 36 on the arming hub 33 and,concurrently therewith, a shoulder 89 on the arming sleeve 51 engages acomplementary shoulder 91 formed in the bore 48 of the arming hub 33.When this occurs the arming hub 33 and arming sleeve 51 are lockedtogether and further rotation of the aforesaid hub and sleeve by thepropeller is prevented.

On Fig. 5 an alternative form of impact member 92 adapted for use withthe present invention is shown, the impact member 92 comprising a hub 93having a plurality of radial arms 94 extending therefrom. The impactmember is secured to the tiring pin 57 in the same manner as the impactdisc 62. It will be understood, however, that when the bomb strikes thesurface of a body of water the impact force applied to the shear pin 58through the impact member 92 is insuflicient to cause the `Shear pin tobreak due to the size of the impact member and the strength of the shearpin and thus the Afuze will not function at this time but as the bombstrikes the bed of a bodyof water suflicient force is applied to theshear pin through the impact member 92 such that the shear pin willbreak or shear whereby the fuse will function to explode the bomb.

It will be further understood, however, that the she-ar pin 58 may be soconstructed as to shear or break in response to a predetermined amountof force applied thereto, such shearing or breaking action resultingfrom the impact force applied to the shear pin as the bomb strikes anobject such, for example, as the surface of a body of water, soft sandor the like, the fuze also being adapted to re in predetermined timedelay relation with respect to impact of the bomb with a target, ifdesired, by employing a time delay element in the detonator. The shearpin 58 may be composed of any material suitable for the purpose whichhas the characteristic of shearing in response to sudden force appliedthereto, it being understood, however, that the strength of the pin maybe varied such that the fuze'will function selectively on the surface ofa body of water, soft sand, and the like or upon the bed of a body ofwater, as the case may be.

Let it be assumed, for the purpose of description, that a bomb employinga fuze of the present invention is released frorn an aircraft in flighttoward a target. As the bomb falls away from the aircraft the yarmingwire 13 is withdrawn from the arm 88 and guide 85 thereby releasing thepropeller for rotation. When the propeller has made a predeterminednumber of revolutions during the free ight of the bomb through the air,the fuze is armed, Figs. 2 and 4. During the arming of the fuze, thearming hub 33 is rotated by the propeller and thus the planetary geararrangement is set in motion and rotative movement is imparted to thearming sleeve 51 whereupon the arming sleeve during rotation thereof isthreaded into the threaded portion 54 of the bore 48 in such a manner asvto withdraw the striker 63 on the tiring pin 57 from locking engagementwith the shutter 65. When this occurs the shutter is moved to an armedposition by the torsion spring 69 and the fuze is armed, Figs. 2 and 4,with the firing pin 57 extended `and the detonator moved into alignmentwith the ring pin and lead-in charge 78. Upon impact of the `bomb withthe target the ring pin is driven into the detonator with sufficientforce to re the detonator, the detonator ignites. the lead-in chargewhich in turn ignites the booster charge, the blast from the boosterbeing adapted to ignite the main charge and explode the bomb.

On Fig. 6 the fuze of the present invention is shown in connection witha portion of a rocket of a well known type and generally indicated byvthe reference character which includes the usual rocket head l96 havingarranged therein the main explosive charge 97, the fuze seat liner orcontainer 98, and the usual booster charge 99 arranged within the liner98. As the rocket described above is the conventional type of rocket,further detailed description thereof is deemed unnecessary.

Secured to the rocket head 98 as by threaded engagement with aninternally threaded nipple 101 formed on the head thereof is anelongated adapter 102, the adapter comprising a cylindrical body .103having a centrally disposed bore 104 extending therethrough. The bore104 is enlarged and threaded as at 105, having threaded engagement withthe cup-shaped member 16 of the fuze whereby the propeller 14 and impactdisc 62 are supported by the adapter 102 at a distance from the outerend of the rocket head 98 thereby to insure that the propeller will bewithin the wind stream and to increase the angle of impact of the rocketwith the target at which tiring will occur.

Arranged within the bore 104 is a plurality of tetryl pellets 106, oneend pellet being in abutting engagement with the disc 27 and the otherend pellet being in substantial abutting engagement with a closure cap107, having threaded engagement with the adapter as at 108, the closurecap also having abutting engagement with an auxiliary booster charge 109disposed within the container 98, the auxiliary booster having abuttingengagement with the booster charge 99. By this arrangement an explosivetrain is provided Lfrom the lead-in charge 78 disposed within the disc27 to the main explosive charge 97.

It will be obvious thatfwhen the rocket is placed in a launching rack tobe red therefrom toward a target, the

. arming wire 13 is attached to the fuze in the same manner asheretofore shown and described and rotation of the propeller 14 isprevented thereby. When the rocket is tired from the launching rack theforward motion thereof withdraws the arming wire from the apertures 84and 87 respectively arranged in the arms 88 and guide 85. Thus the fuzewill be armed during the free llight of the rocket toward the target andupon impact therewith the fuze will function as heretofore describedthereby to explode the rocket. The operation of the fuze will be bestunderstood by consideration of a specific example.

Briefly stated in summary, the present invention contemplates theprovision of a new and improvedv fuze in l which means are employed forpreventing premature firing thereof due to suddnshock received therebybefore the propeller has'made `a predetermined number of revoluwhich theinvention pertains, after understanding the invention, that variouschanges and modifications may be made without departing fromvthe spiritand scope of the invention, and it is intended, therefore, in theappended claims to cover all such changes and modications.

The invention herein described and claimed may be manufactured and usedby or for the Government of the United States of America forgovernmental purposes without payment of any royalties thereon ortherefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A mechanical impact fuze of the class described comprising a casing,an explosive charge arranged within said casing, a rotatable shutterreleasably supported within the casing in an initial safe position andhaving a detonator adapted to be brought into alignment with a firingpin as the shutter isV rotated to an armed position, means for rotatingsaid shutter from said initial safe position to the armed position asVthe shutter 'is released, a firing pin having an impact device attachedthereto, means including a threaded sleeve having a slot formed in oneend thereof for rotatably supporting the firing pin for axial movementtherewith in a direction outwardly of the casing and in initialreleasable locking engagement with said shutter, said firing pin beingadapted to release the shutter when the firing pin has been movedrotatably and axially a predetermined amount, means for rotating saidsleeve, means on said firing pin disposed within said slot forpreventing axial movement thereof in a direction outwardly until saidsleeve is rotated, means on said firing pin in engagement with saidrotating means for preventing axial movement of the firing pin in adirection inwardly until said sleeve is moved outwardly a predeterminedamount, and means for releasably securing the ring pin to said sleeve,said last named means being adapted to release said firing pin forsliding movement inwardly within said sleeve and with respect thereto inresponse to a sudden impact received by said impact device thereby to resaid detonator and explode the explosive charge.

2. A mechanicalimpact fuze of the class described comprising a casing, arotatable shutter releasably supported within the casing in an initialsafe position and having a detonator adapted to be brought intoalignment with a firing pin as the shutter is rotated to an armedposition, means for rotating said-shutter from said initial safeposition to the armed position when the shutter is released, a firingpin for firing the detonator in response to a sudden impactreceived'thereby when the shutter is in said 'armed position, meansincludinga threaded sleeve for rotatably supporting the firing pin foraxial movement therewith in a direction outwardly of the casing and ininitial releasable locking engagement with said shutter,

said firing pin being adapted to release the shutter whenthe firing pinhas been moved rotatably and axially outwardly of the casing a'predetermined amount, means including a hub for rotating said sleeve,shearable means for securing the firing pin to said sleeve and adaptedto be severed to' release said firing pin upon said impact, non*shearable 4means secured to said firing'p'in and disposed within arecess arranged within the inner endsurface of the sleeve for relievingthe torsional stress on said shearable means as the sleeve rotates andpreventing axial movement of the ring pin in an outward direction whensaid fuze is in an initial safe position, and an impact member normallyin engagement with said hub for preventing axial movement of said firingpin in an inward direction when said fuze is in said initial position.

3. A mechanical impact fuze of the class described comprising a casing,an explosive charge arranged within said casing, a rotatable shutterreleasably arranged within the casing in an initial safe position andhaving a detonator adapted to be brought into alignment with a firingpin as the shutter is rotated to an armed position, means for rotatingsaid shutter from said initial safe position to said armed position asthe shutter is released, a firing pin, means including a threaded sleevefor rotatably supporting the firing pin for axial movement therewith ina direction outwardly of thecasing and in initial releasable lockingengagement with said shutter, said firing pin being adapted to releasethe shutter when the tiring pin has been moved rotatably and axiallyoutwardly a predetermined amount by said sleeve, means including a hubconnected to said sleeve for rotating the sleeve, shearable means forreleasably securing the firing pin to said sleeve, said last named meansbeing adapted to be severed and release said firing pin for slidingmovement inwardly within the sleeve and with respect thereto in responseto a sudden impact received by said impact member thereby to fire saiddetonator, non-shearable means providing axial movement of the firingpin inwardly of the sleeve as the shearable means is severed and arotational driving connection therewith for relieving the torsionalstress on said securing means as the sleeve rotates during outwardmovement of the sleeve and pin, said non-shearable means being adaptedto prevent outward movement of said firing pin until said sleeve isrotated, an impact member normally in vengagement with said hub forpreventing axial movement of said firing pin in an inward directionuntil said sleeve is moved rotatably and axially outwardly, and meansfired by said detonator for exploding said explosive charge.

4. A mechanical impactrocket fuze of the class described comprising acasing, a rotatable shutter releasably arranged within said casing in aninitial safe position, a detonator disposed within said shutter andadapted to be brought into alignment with a firing pin as the shutter isrotated to an armed position, means including a spring for rotating saidshutter from said initial safe position to said armed position as theshutter is released, an arming hub rotatably supported within saidcasing, an arming sleeve rotatably arranged within said arming hub andadapted to be moved axially in an outward direction with respect to saidhub when rotated, threaded meanson said arming hub, complementarythreaded means on said arming sleeve in engagement with said threadedmeans on the hub for moving the arming sleeve axially outwardly to saidarmed position as the hub rotates, means including a propelleroperatively connected to said arming hub for rotating the arming hub, afiring pin releasably secured within the sleeve for rotation and axialmovement therewith and adapted to releasably lock the shutter in saidsafe position until the arming sleeve has been moved axially outwardly apredetermined amount, shearable means for releasably securing the firingpin to the sleeve and adapted to be severed and release the firing pinfor sliding movement inwardly within said sleeve and with respectthereto in response to a sudden impact received by said firing pin,non-shearable means providingaxial movement of the firing pin inwardlyas said shearable means is severed and a rotational driving connectiontherewith for relieving the torsional stress on said securing means asthe sleeve is rotated said non-shearable means being adapted to preventoutward movement of said ring pin until said sleeve is rotated, and animpact UNITED STATES PATENTS 2,131,037 Brayton Sept. 27, 1938 10 BoldFeb. 13, 1940 Fischer Apr. 2, 1946 Errig et al July 30, 1946 FOREIGNPATENTS Great Britain June 19, 1919 Great Britain Aug. 27, 1926

